1. Field of the Disclosure
This disclosure relates to plasma deposition of a thin film.
2. Description of Related Art
Recently, as existing energy sources such as petroleum and coal are expected to be depleted, interest in alternative energy sources for replacing the existing energy sources is increasing. Among alternative energy sources, solar cells that generate electric energy from solar energy have received attention.
A solar cell may be classified into a solar cell using solar heat and a solar cell using solar light. A solar cell using solar light may be formed using single crystal silicon, polysilicon, amorphous silicon, etc. The solar cell formed of crystalline silicon is costly, considering its heat generation efficiency, and is manufactured through a complex process.
Because of these reasons, interests in a thin film solar cell are recently increasing and a thin film solar cell with high efficiency has been actively developed.
A plasma enhanced chemical vapor deposition (PECVD) apparatus using plasma is used to form thin films formed of amorphous silicon or microcrystalline silicon. The amorphous or microcrystalline silicon thin films can be used for a thin film solar cell, a thin film transistor, etc.
Use of a PECVD apparatus that generally uses a high frequency power may increase a deposition rate of the thin film, but may cause a reduction in the quality of the thin film. The PECVD apparatus has to uniformly and densely deposit a radical, for example SiH3, on the surface of a substrate so as to improve the quality of the thin film. However, if the PECVD apparatus deposits the thin film at a very high deposition rate, the radical does not deposit uniformly and densely on the surface of the substrate.